GRAND RAPIDS -- Retirement was supposed to be a time for anthropologist and best-selling author Napolean Chagnon to reflect on a career that brought him both celebrity and controversy for his findings about violence and primitive man.

He and his wife, Carlene, retreated a year ago to a spacious, modern house on 15 pristine acres in northern lower Michigan, about 10 miles south of Traverse City.

In 1968, Chagnon wrote "Yanomamo: The Fierce People," a best-selling book about a remote, prehistoric Venezuelan tribe. He spent 18 months studying the tribe before the publication of the book, which startled many in his field by concluding that man is not so much a "noble savage" as a creature inclined toward violence.

"I kind of shocked the profession by telling it the way it is," he told The Grand Rapids Press for a story Sunday.

The book made Chagnon perhaps the pre-eminent anthropologist of the time. Over the years, however, academics started taking opposite sides as they weighed the importance of biology against culture as factors in shaping the human race.

Now Chagnon is a key figure in Darkness in El Dorado, a book released in mid-November that accuses him of faking documentary film scenes, tampering with Yanomami customs and distorting data to suit his thesis about man's natural inclination toward violence.

Author Patrick Tierney also accuses Chagnon of routinely exaggerating warfare and ritual fighting among the Yanomami and corrupting their culture by giving them machetes as reward for their cooperation.

In his most explosive claim, Tierney linked Chagnon and University of Michigan physician and geneticist James Neel to the deaths of hundreds of Yanomami in 1968, when they administered a measles vaccine called Edmonston B that Tierney suggests caused the disease.

Neel, considered by many to be the father of human genetics, died in February of prostate cancer at age 84.

In recent weeks, Chagnon has spent much of his time defending himself in telephone interviews and consulting colleagues by e-mail.

"I've got two obligations," he says. "One is to my community of academics who realize what Tierney has done. But I also have a family and all my family members whose name is Chagnon are embarrassed and disturbed by this. It's on their behalf that I am trying to win this battle."

Darkness in El Dorado has itself come under scrutiny, though its author stands by its contents.

The American Anthropological Association last month appointed a committee to investigate issues raised by the book. Meanwhile, institutions such as the National Academy of Sciences, the University of Michigan and the University of California at Santa Barbara, where Chagnon taught for 15 years, weighed in with statements condemning Tierney's book.

Nancy Cantor, provost of the University of Michigan, issued a statement on Nov. 13 saying the school "has carefully and thoroughly investigated many of the major claims made ... and the evidence we have uncovered supports the conclusion that these claims are false."

"The book is a fraud," said University of New Mexico anthropologist Kim Hill, an expert on South American primitive cultures who said he has read Tierney's book and checked each of its 1,599 footnotes. "The evidence that is used to build its case is also fraudulent."

Hill said Tierney consistently misstates the sources he cites, quoting out of context to shed the worst light on Chagnon or Neel.

Tierney's most serious claim, that Neel and Chagnon may have caused a measles epidemic, appears to be crumbling in the face of science.

In making his case, Tierney quotes Dr. Mark Papania, chief of measles eradication for the federal Centers for Disease Control and Prevention. Papania later said his remarks were taken out of context.

Contacted by telephone, Tierney said he "absolutely" stands by the accuracy of his book.

He contended that Hill is an ally of Chagnon who is "simply repeating the party line." As for the University of Michigan, Tierney maintained that officials there were trying to cover the school's complicity in Neel's alleged wrongdoing.